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Texas Instruments SN74S138AN — Logic ICs
Texas Instruments

SN74S138AN 74S Decoder/Demultiplexer, 1 x 3:8, 16-DIP

MPNSN74S138AN
End of Life

Texas Instruments 74S series SN74S138AN, Decoder/Demultiplexer, 1 x 3:8 circuit, 4.75V ~ 5.25V supply, 400µA / 8mA output drive, 16-DIP through-hole, 0°C to 70°C.

$2.54Ref. price · indicative, final on quote
SN74S138AN datasheet
Packaging16-DIP (0.300", 7.62mm)
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MOQ1 pcs
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Specifications

SN74S138AN Technical Specifications
ParameterValue
TypeDecoder/Demultiplexer
Series74S
Mounting typeThrough Hole
Voltage4.75V ~ 5.25V
Voltage supply sourceSingle Supply
Current - output high, low400µA, 8mA
Operating temperature0°C ~ 70°C
Circuit1 x 3:8
PackageTube
Case16-DIP (0.300\", 7.62mm)
Independent circuits1

Product details

1-of-8 decoder/demultiplexer in a 16-pin DIP

The Texas Instruments SN74S138AN is a 74S-series 1-of-8 decoder/demultiplexer that takes a 3-bit binary input and asserts one of eight active-low outputs. It is commonly used in address decoding for memory-mapped I/O, data routing, or generating chip-select signals in legacy 5V TTL systems. The 16-DIP (0.300", 7.62mm) through-hole package makes it a direct fit for breadboards, prototype boards, and existing PCB layouts that use plated-through holes.

5V supply rail and commercial temperature range

The SN74S138AN operates from a single 4.75V to 5.25V supply, matching standard 5V TTL logic levels. For industrial or automotive environments requiring -40°C or wider range, a 74LS or 74HC variant with extended temperature would be needed.

Output drive: 400 µA high, 8 mA low

The output stage is rated for 400 µA sourcing (logic high) and 8 mA sinking (logic low). This is typical for 74S-series TTL and drives standard TTL loads directly, but it will not directly drive LEDs, relays, or high-impedance CMOS inputs without a buffer. Fan-out to up to 10 standard TTL loads is fine; fan-out to CMOS inputs requires a pull-up resistor or a level shifter.

Frequently asked questions

Is SN74S138AN the same as 74LS138?

No. The SN74S138AN is a 74S-series Schottky TTL device, while the 74LS138 is a low-power Schottky variant. The 74S series offers higher speed (propagation delay around 10 ns typical) but draws more supply current. The 74LS138 runs slower (around 20 ns typical) but uses less power. Pinout and function are identical, so they are drop-in replacements for each other in most designs if the timing and power budgets allow.

Does SN74S138AN come in a DIP-16 package?

Yes, it comes in a 16-DIP (0.300", 7.62mm) through-hole package, also referred to as 16-PDIP in the supplier device package listing.

What is the function of SN74S138AN?

It is a 1-of-8 decoder/demultiplexer. It takes a 3-bit binary address input and asserts one of eight active-low outputs. It can also function as a demultiplexer by using an enable input as the data line.